For knowledge representation we study the logical foundation of ontology and fine-grain semantic representation. We also study near-synonyms to identify fine-grain differences between synonyms. These processes enable us to better understand meaning representation and meaning composition. We will remodel the current ontology structures of WordNet, HowNet, and FrameNet to achieve a better and more unified representation, called Extended-HowNet. In addition, we will study modal logics and integrate modal logic systems into a unified framework and develop automated inference and theorem proving methods based on the logical framework.